There has been proposed an invention in which, when attaching an intake valve and an exhaust valve to be used for the engine of an automobile or the like to the intake port and exhaust port of a cylinder head, for example, a rocker arm connected to a valve stem is turned around the fulcrum of a mechanical lash adjuster so as to automatically adjust valve clearance between the valve such as an intake valve and the rocker arm by driving of the mechanical lash adjuster (see Patent Document 1).
In addition, there has been proposed an invention in which, for keeping the chain tension of a cam drive chain or the like to be used for the engine of an automobile or the like constant, the tension is automatically adjusted by driving of a mechanical adjuster (chain tensioner) (see Patent Document 2).    Patent Document 1: Japanese Published Unexamined Utility Model Application No. H03-1203    Patent Document 2: Japanese Published Unexamined Patent Application No. 2001-124159